Epidemiological and microbiological investigation of an outbreak of severe disease from Shiga toxin-producing Escherichia coli O157 infection associated with consumption of a slaw garnish

Lisa Byrne*, Natalie Adams, Kirsten Glen, Tim Dallman, Ishani Kar-Purkayastha, Gillian Beasley, Caroline Willis, Simon Padfield, Goutam Adak, Claire Jenkins

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Investigating outbreaks of Shiga toxin-producing Escherichia coli (STEC) in England is a priority due to the potential severity of disease. However, there are often challenges in investigating outbreaks due to the small numbers of cases, poor patient recall, and low levels of bacteria that are challenging to detect in food samples using traditional laboratory culture techniques, and frequently a source is not identified. In September 2014, we investigated an STEC O157 outbreak associated with consuming a slaw garnish, and we report our findings here. Twenty confirmed cases were identified. Outbreak cases were interviewed, and menus reviewed to identify dishes consumed outside the home. Cases shared a history of eating meals at different chain restaurants. Analysis of menu items indicated shared consumption of slaw garnishes by 85.6% cases, although just 35.7% reported consuming them during interviews. Whole-genome sequencing linked cases where interpretation of the multilocus variable number tandem repeat analysis profile was obscured and indicated that the strain originated from a domestic (i.e., United Kingdom) source. Traceback identified that carrots and cabbages grown in the United Kingdom were the likely source of infection. Samples of products were examined, but STEC was not recovered. Epidemiological investigations linked the outbreak to consumption of a slaw garnish, which was poorly recalled by cases, and likely comprised of domestically produced raw vegetables. The causative organism was not isolated from food samples, and we conclude that future investigations should include sampling of animals and wildlife in the vicinity of farms where implicated produce is grown.

Original languageEnglish
Pages (from-to)1161-1168
Number of pages8
JournalJournal of Food Protection
Issue number7
Publication statusPublished - Jul 2016

Bibliographical note

Funding Information:
We thank all those involved in the Outbreak Control Team, including Nicola Elviss, Frieda Jorgensen, Moira Kaye, and Lorraine Sadler-Reeves. We thank Andrew Fox from the PHE Food, Water and Environment Laboratories, Eleanor Anderson and Mary Hanson from Health Protection Scotland, and Kristina Poole, Girija Dabke, Juli Treacy, Wendy Rice, Noel McCarthy, Jeremy Hawker, Richard Elson, Ian Fisher, Chris Lane, and Gauri Godbole from PHE. We thank Dranzenka Tubin-Delic, Kirsten Stone, and Tracy Bishop from the Food Standards Agency. Thanks to the environmental health practitioners who visited all of the premises, in particular Melanie Henbest. The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR, the Department of Health, or Public Health England.

Publisher Copyright:
Copyright ©, International Association for Food Protection.

Copyright 2016 Elsevier B.V., All rights reserved.


  • Foodborne disease
  • Infectious disease
  • Outbreak
  • Shiga toxigenic Escherichia coli


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